I have a '96 Ram 1500 SLT with 129k miles (318 CI) and an automatic that the previous owner/friend had rebuilt by the best shop in the area at 105k miles. Back on New Year’s Day, with HeyYou’s help, I got rid of a P0720 tranny code & its symptoms by replacing the OSS. Now, as of Friday, the truck began to feel sluggish from a stop. I came to realize that the trannie is now starting off in 2nd gear. If I put the selector in 1st & shift manually, everything works fine. Also, I ran a scan...no codes thrown. I’m fed up… the weekend before I replaced the rear wheel cylinders and bled the whole brake system because the right one decided to bleed out.

Anyway, I’ve seen where it’s most likely the gov pressure solenoid or pressure sensor, but could it be something else? I’m pretty sure these things were changed at 117k when I also had it in a shop to change the engine oil pump. At the time I mentioned the symptoms of the bad OSS to them (no CEL on, so didn’t know P0720 was there). So, at their request, I let them take a look at it. They were unsuccessful but their vague ticket shows the parts they threw at it as: solenoid $45, sensor 63, solenoid 59, speed sensor 38.

 

Try this test:

Unplug the 8-pin connector at the trans. Drivers side, about halfway back.

Take the truck for a test drive, you will have to shift manually, as there will be zero automatic function.

If it shifts when you tell it to, chances are good the governor pressure sensor/solenoid are giving you fits. Since this trans was ostensibly rebuilt about 20K miles ago..... and you are having sensor failures left and right..... I would be real curious what brand parts they put in there.

If you decide to change them out, Electrical Advantage (I think, seller on EBay) has the borg warner heavy duty solenoid with pressure sensor for around 100 bucks.

 

OK, thanks. I'll try to do this test at home tonight.

In retrospect, it's feasible to me that the second shop replaced the tranny shop's perfectly good, better-quality gov pressure solenoid with a cheaper one. I don't think the 2nd shop touched the OSS...my truck continued to have problems until I replaced it and it had a little bit of fine metal sludge on it...not really the OSS's fault.

 

Must be warmer down by you...... Looks horribly winter-like out there at the moment here.

 

Yup...57 degF right now here in Huntsville, Alabama...balmy compared to what it has been the past few weeks.

 

OK, I pulled the round 8-pin connector & drove it. Here’s how it went:

I put the selector in R, it went into reverse and it backed it up fine. Then, I went to N and then went immediately down to 1, not pausing at D or 2. Upon accelerating it felt like it was in 1st, moved it to 2 & the transmission upshifted, went to D and it upshifted again. Then, as I slowed down approaching a stop sign, I went to 2 and it downshifted, but when I went down to 1, I didn’t notice a downshift.

In summary…it would downshift when moving the selector from D to 2 while slowing down or stopped, but it would not downshift when going from 2 to 1 while slowing down or stopped. Leaving the selector in 1 while stopped, upon accelerating again, the transmission didn’t upshift again until I went from 2 to D in the process, so I’m assuming it was starting off in 2nd even though the selector was at 1 (Note: to me, it didn’t seem as sluggish upon initial acceleration though).

However, at any point, if I stopped and moved the selector up to N, R, or P, then moved it quickly down to 1 like I did initially, it would upshift when going into 2 and then again into D. On the other hand, if I instead paused briefly at D and 2 when going from N down to 1, the transmission seemed to start in 2nd gear because it would not upshift until going from 2 to D in the process of going through the selections.

Help regarding what this all means would be greatly appreciated.

 

Maybe normal...... or, it might be a sticking valve in the valve body.....

 

I’ve told the following on this forum awhile back when trying to figure out the bad OSS symptoms: I bought this truck about 2 yrs ago from a friend who went & bought a new Ram cuz his dog had ripped up most of the wires in the vicinity of the transmission trying to get to a cat sheltering on the trans. I got a complete wire harness from a boneyard & basically soldered the wires at the harness's main trunk where it comes down from the engine bay back to the trans.
We’ve had much colder temperatures than normal…if I had a weak solder somewhere, I'm wondering if the cold temperatures could've caused it to become brittle enough to break and cause this issue. If this sounds feasible, is there a specific wire that I should dig out of the sheathing & the heat shrink to check first?

 

If you don't already have one, grab the 96 service manual from the Service Manual thread in the faq section. Have a look at the wiring diagrams, and check the circuits for the governor pressure sensor, and solenoid. Just do a continuity check, no need to dig the joints out, unless you don't have continuity. (but, if that were the case, you would have some codes.)

I would be real tempted to pull the pan, drop the filter, and see what you find..... maybe even clean out the valve body..... (though that is a jigsaw puzzle....) adjust the bands?

 

Good idea on the continuity check. I may clean the valve body depending on the results of that.

As far as the bands go, I adjusted them last spring (4k-5k miles ago I think) and I changed the fluid and filter while I was at it when I was having the symptoms of the bad OSS. I checked the fluid the other day and it still looks/smells like fresh fluid.